An auspicious landscape: Quantifying transient glacial incision in the Patagonian Andes from ~6 Ma to present

2021 ◽  
Author(s):  
Chelsea Willett ◽  
Keith Ma ◽  
Mark Brandon ◽  
Jeremy Hourigan ◽  
Elizabeth Christeleit ◽  
...  
Keyword(s):  
Source Region ◽  
Fold Increase ◽  
Erosion Rates ◽  
Local Erosion ◽  
Characteristic Features ◽  
Mountainous Landscape ◽  
Uplift And Erosion ◽  
Patagonian Andes ◽  
Natural Laboratory

<p>The topography, climate, and geology of the central Patagonian Andes provide an auspicious natural laboratory to track long-term rates of erosion in a dynamic mountainous landscape. Herein, we report a mountain-scale record of erosion rates in the central Patagonian Andes from >10 million years (Ma) ago to present, which covers the transition from a fluvial to alpine glaciated landscape. Apatite (U-Th)/He ages of 72 granitic cobbles from alpine glacial deposits show slow erosion before ~6 Ma ago, followed by a two- to three-fold increase in the spatially averaged erosion rate of the source region after the onset of alpine glaciations and a 15-fold increase in the top 25% of the distribution. This transition is followed by a pronounced decrease in erosion rates over the past ~3 Ma. We ascribe the pulse of fast erosion to local deepening and widening of valleys, which are characteristic features of alpine glaciated landscapes. The subsequent decline in local erosion rates may represent a return toward a balance between rock uplift and erosion.</p>

scholarly journals Transient glacial incision in the Patagonian Andes from ~6 Ma to present

2020 ◽  
Vol 6 (7) ◽  
pp. eaay1641 ◽  
Author(s):  
C. D. Willett ◽  
K. F. Ma ◽  
M. T. Brandon ◽  
J. K. Hourigan ◽  
E. C. Christeleit ◽  
...  
Keyword(s):  
Erosion Rate ◽  
Source Region ◽  
Fold Increase ◽  
Erosion Rates ◽  
The Past ◽  
Threefold Increase ◽  
Local Erosion ◽  
Characteristic Features ◽  
Uplift And Erosion ◽  
Patagonian Andes

We report a mountain-scale record of erosion rates in the central Patagonian Andes from >10 million years (Ma) ago to present, which covers the transition from a fluvial to alpine glaciated landscape. Apatite (U-Th)/He ages of 72 granitic cobbles from alpine glacial deposits show slow erosion before ~6 Ma ago, followed by a two- to threefold increase in the spatially averaged erosion rate of the source region after the onset of alpine glaciations and a 15-fold increase in the top 25% of the distribution. This transition is followed by a pronounced decrease in erosion rates over the past ~3 Ma. We ascribe the pulse of fast erosion to local deepening and widening of valleys, which are characteristic features of alpine glaciated landscapes. The subsequent decline in local erosion rates may represent a return toward a balance between rock uplift and erosion.

scholarly journals Lithological control on the landscape form of the upper Rhône Basin, Central Swiss Alps

2016 ◽  
Vol 4 (1) ◽  
pp. 253-272 ◽  
Author(s):  
Laura Stutenbecker ◽  
Anna Costa ◽  
Fritz Schlunegger
Keyword(s):  
Swiss Alps ◽  
Short Term ◽  
Linear Discriminant ◽  
Erosion Rates ◽  
Digital Elevation ◽  
Discriminant Analyses ◽  
Controlling Variables ◽  
Uplift And Erosion ◽  
Landscape Morphology

Abstract. The development of topography depends mainly on the interplay between uplift and erosion. These processes are controlled by various factors including climate, glaciers, lithology, seismic activity and short-term variables, such as anthropogenic impact. Many studies in orogens all over the world have shown how these controlling variables may affect the landscape's topography. In particular, it has been hypothesized that lithology exerts a dominant control on erosion rates and landscape morphology. However, clear demonstrations of this influence are rare and difficult to disentangle from the overprint of other signals such as climate or tectonics. In this study we focus on the upper Rhône Basin situated in the Central Swiss Alps in order to explore the relation between topography, possible controlling variables and lithology in particular. The Rhône Basin has been affected by spatially variable uplift, high orographically driven rainfalls and multiple glaciations. Furthermore, lithology and erodibility vary substantially within the basin. Thanks to high-resolution geological, climatic and topographic data, the Rhône Basin is a suitable laboratory to explore these complexities. Elevation, relief, slope and hypsometric data as well as river profile information from digital elevation models are used to characterize the landscape's topography of around 50 tributary basins. Additionally, uplift over different timescales, glacial inheritance, precipitation patterns and erodibility of the underlying bedrock are quantified for each basin. Results show that the chosen topographic and controlling variables vary remarkably between different tributary basins. We investigate the link between observed topographic differences and the possible controlling variables through statistical analyses. Variations of elevation, slope and relief seem to be linked to differences in long-term uplift rate, whereas elevation distributions (hypsometry) and river profile shapes may be related to glacial imprint. This confirms that the landscape of the Rhône Basin has been highly preconditioned by (past) uplift and glaciation. Linear discriminant analyses (LDAs), however, suggest a stronger link between observed topographic variations and differences in erodibility. We therefore conclude that despite evident glacial and tectonic conditioning, a lithologic control is still preserved and measurable in the landscape of the Rhône tributary basins.

scholarly journals Long-term erosion rates as a function of climate derived from the impact crater inventory

2019 ◽  
Vol 7 (2) ◽  
pp. 459-473 ◽  
Author(s):  
Stefan Hergarten ◽  
Thomas Kenkmann
Keyword(s):  
Impact Crater ◽  
Fold Increase ◽  
Regional Effect ◽  
Tropical Zone ◽  
Erosion Rates ◽  
Continental Scale ◽  
River Loads ◽  
The Impact

Abstract. Worldwide erosion rates seem to have increased strongly since the beginning of the Quaternary, but there is still discussion about the role of glaciation as a potential driver and even whether the increase is real at all or an artifact due to losses in the long-term sedimentary record. In this study we derive estimates of average erosion rates on the timescale of some tens of millions of years from the terrestrial impact crater inventory. This approach is completely independent from all other methods to infer erosion rates such as river loads, preserved sediments, cosmogenic nuclides, and thermochronometry. Our approach yields average erosion rates as a function of present-day topography and climate. The results confirm that topography accounts for the main part of the huge variation in erosion on Earth, but also identifies a significant systematic dependence on climate in contrast to several previous studies. We found a 5-fold increase in erosional efficacy from the cold regimes to the tropical zone and that temperate and arid climates are very similar in this context. Combining our results into a worldwide mean erosion rate, we found that erosion rates on the timescale of some tens of millions of years are at least as high as present-day rates and suggest that glaciation has a rather regional effect with a limited impact at the continental scale.

Climate Oscillations from Mountain Uplift and Erosion are Damped by Bioactivity

2021 ◽  
Author(s):  
Dennis Höning
Keyword(s):  
Plate Boundaries ◽  
Climate Oscillations ◽  
Biosphere 2 ◽  
Erosion Rates ◽  
Wide Range ◽  
1D Model ◽  
Uplift And Erosion ◽  
Steep Slopes

<p>Earth’s long-term carbonate-silicate cycle is continuously perturbed by processes of mountain building and erosion. Mountain uplift near convergent plate boundaries causes steep slopes, which in turn imply high rates of continental erosion. Erosion rates ultimately affect the weatherability and thereby the regulation of Earth’s climate. Using a simple 1D-model that includes the outlines processes, I investigate the resulting climate oscillations over timescales from thousands to millions of years. With a simple model of the long-term carbon cycle that includes biological enhancement of weathering and marine biogenic calcite precipitation, I study the role of Earth’s biosphere in damping these oscillations [1]. I show that both mechanisms play a role: Biological enhancement of weathering damps oscillations mainly on timescales > 1 Ma and marine calcification mainly on shorter timescales. Altogether, the results indicate that Earth’s biosphere contributes to a stable climate over a wide range of timescales.</p><p>In the context of anthropogenic emissions, a dramatic elevation in the atmospheric CO<sub>2</sub> and related temperature is known to damage Earth’s biosphere [2] and may even trigger runaway processes [3]. The results presented here indicate that a damaged biosphere may furthermore cause the Earth system to react more sensitive to oscillations from geological forcing and may also affect climate recovery.</p><p>References:</p><p>[1] Höning 2020, Geochem. Geophys. Geosyst. 21(9), e2020GC009105<br>[2] Sully et al. 2019, Nat. Comm. 10, 1264<br>[3] Lenton 2013, Annu. Rev. Environ. Resour. 38, 1-29</p>

scholarly journals Soil erosion by snow gliding – a first quantification attempt in a subalpine area in Switzerland

2014 ◽  
Vol 18 (9) ◽  
pp. 3763-3775 ◽  
Author(s):  
K. Meusburger ◽  
G. Leitinger ◽  
L. Mabit ◽  
M. H. Mueller ◽  
A. Walter ◽  
...  
Keyword(s):  
Land Use ◽  
Soil Erosion ◽  
Land Cover ◽  
Sediment Yield ◽  
Soil Loss ◽  
Water Erosion ◽  
Erosion Rates ◽  
The Difference ◽  
Snow Gliding

Abstract. Snow processes might be one important driver of soil erosion in Alpine grasslands and thus the unknown variable when erosion modelling is attempted. The aim of this study is to assess the importance of snow gliding as a soil erosion agent for four different land use/land cover types in a subalpine area in Switzerland. We used three different approaches to estimate soil erosion rates: sediment yield measurements in snow glide depositions, the fallout radionuclide 137Cs and modelling with the Revised Universal Soil Loss Equation (RUSLE). RUSLE permits the evaluation of soil loss by water erosion, the 137Cs method integrates soil loss due to all erosion agents involved, and the measurement of snow glide deposition sediment yield can be directly related to snow-glide-induced erosion. Further, cumulative snow glide distance was measured for the sites in the winter of 2009/2010 and modelled for the surrounding area and long-term average winter precipitation (1959–2010) with the spatial snow glide model (SSGM). Measured snow glide distance confirmed the presence of snow gliding and ranged from 2 to 189 cm, with lower values on the north-facing slopes. We observed a reduction of snow glide distance with increasing surface roughness of the vegetation, which is an important information with respect to conservation planning and expected and ongoing land use changes in the Alps. Snow glide erosion estimated from the snow glide depositions was highly variable with values ranging from 0.03 to 22.9 t ha−1 yr−1 in the winter of 2012/2013. For sites affected by snow glide deposition, a mean erosion rate of 8.4 t ha−1 yr−1 was found. The difference in long-term erosion rates determined with RUSLE and 137Cs confirms the constant influence of snow-glide-induced erosion, since a large difference (lower proportion of water erosion compared to total net erosion) was observed for sites with high snow glide rates and vice versa. Moreover, the difference between RUSLE and 137Cs erosion rates was related to the measured snow glide distance (R2 = 0.64; p < 0.005) and to the snow deposition sediment yields (R2 = 0.39; p = 0.13). The SSGM reproduced the relative difference of the measured snow glide values under different land uses and land cover types. The resulting map highlighted the relevance of snow gliding for large parts of the investigated area. Based on these results, we conclude that snow gliding appears to be a crucial and non-negligible process impacting soil erosion patterns and magnitude in subalpine areas with similar topographic and climatic conditions.

scholarly journals No Observed Adverse Effects on Health Were Detected in Adult Beagle Dogs When Fed a High-Calcium Diet for 40 Weeks

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1799
Author(s):  
Jujhar Atwal ◽  
Jonathan Stockman ◽  
Matthew Gilham ◽  
David Allaway ◽  
Helen Renfrew ◽  
...  
Keyword(s):  
Filtration Rate ◽  
Fold Increase ◽  
Diet Group ◽  
Test Diet ◽  
Beagle Dogs ◽  
Adverse Health Effects ◽  
Mineral Balance ◽  
High Calcium ◽  
High Calcium Diet

The implications of long-term high calcium (Ca) intake are well documented in growing dogs and in adult dogs of large breed size, however, the consequences on other breeds and breed sizes are yet to be determined. Eighteen neutered adult beagles, nine males and nine females aged 1.4–4.4 years, were randomized to control or test diets providing in g∙4184 kJ−1 (1000 kcal−1): 1.44 and 7.19 total Ca balanced with 1.05 and 4.25 total phosphorus, respectively, for 40 weeks. Health parameters, ultrasound scans, radiographs, glomerular filtration rate, and mineral balance were measured at eight-week intervals. All dogs remained healthy with no measured evidence of orthopedic, urinary, or renal disease. The test diet resulted in a 5.2 fold increase in fecal Ca excretion. Apparent Ca digestibility (%) and Ca balance (g/d) did not significantly (p > 0.05) change from baseline in the test diet group, although dogs displayed a positive Ca balance (maximum at week 8, 1.11 g/d with 95% CI (0.41, 1.80)) before a neutral Ca balance was restored at week 32. Despite an initial positive Ca balance, we can conclude that no measurable adverse health effects were observed as a result of the test diet fed in this study in beagles over a period of 40 weeks.

scholarly journals MATLAB Virtual Toolbox for Retrospective Rockfall Source Detection and Volume Estimation Using 3D Point Clouds: A Case Study of a Subalpine Molasse Cliff

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 75
Author(s):  
Dario Carrea ◽  
Antonio Abellan ◽  
Marc-Henri Derron ◽  
Neal Gauvin ◽  
Michel Jaboyedoff
Keyword(s):  
Point Cloud ◽  
Natural Hazard ◽  
Point Clouds ◽  
Volume Estimation ◽  
Natural Phenomena ◽  
Frequency Distributions ◽  
Erosion Rates ◽  
3D Point Clouds

The use of 3D point clouds to improve the understanding of natural phenomena is currently applied in natural hazard investigations, including the quantification of rockfall activity. However, 3D point cloud treatment is typically accomplished using nondedicated (and not optimal) software. To fill this gap, we present an open-source, specific rockfall package in an object-oriented toolbox developed in the MATLAB® environment. The proposed package offers a complete and semiautomatic 3D solution that spans from extraction to identification and volume estimations of rockfall sources using state-of-the-art methods and newly implemented algorithms. To illustrate the capabilities of this package, we acquired a series of high-quality point clouds in a pilot study area referred to as the La Cornalle cliff (West Switzerland), obtained robust volume estimations at different volumetric scales, and derived rockfall magnitude–frequency distributions, which assisted in the assessment of rockfall activity and long-term erosion rates. An outcome of the case study shows the influence of the volume computation on the magnitude–frequency distribution and ensuing erosion process interpretation.

Geologic Controls on Regional and Local Erosion Rates of Three Northern Gulf of Mexico Barrier-Island Systems

2013 ◽  
Vol 63 ◽  
pp. 32-45 ◽  
Author(s):  
David C. Twichell ◽  
James G. Flocks ◽  
Elizabeth A. Pendleton ◽  
Wayne E. Baldwin
Keyword(s):  
Gulf Of Mexico ◽  
Barrier Island ◽  
Northern Gulf Of Mexico ◽  
Erosion Rates ◽  
Local Erosion ◽  
Geologic Controls

Erosion rates of the New Zealand Southern Alps reflect long-term tectonics and transient climate

2021 ◽  
Author(s):  
Duna Roda-Boluda ◽  
Taylor Schildgen ◽  
Hella Wittmann-Oelze ◽  
Stefanie Tofelde ◽  
Aaron Bufe ◽  
...  
Keyword(s):  
New Zealand ◽  
Strike Slip ◽  
Southern Alps ◽  
Fault System ◽  
Tectonic Deformation ◽  
Seismic Cycle ◽  
Erosion Rates ◽  
Alpine Fault ◽  
Oblique Convergence

&lt;p&gt;The Southern Alps of New Zealand are the expression of the oblique convergence between the Pacific and Australian plates, which move at a relative velocity of nearly 40 mm/yr. This convergence is accommodated by the range-bounding Alpine Fault, with a strike-slip component of ~30-40 mm/yr, and a shortening component normal to the fault of ~8-10 mm/yr. While strike-slip rates seem to be fairly constant along the Alpine Fault, throw rates appear to vary considerably, and whether the locus of maximum exhumation is located near the fault, at the main drainage divide, or part-way between, is still debated. These uncertainties stem from very limited data characterizing vertical deformation rates along and across the Southern Alps. Thermochronology has constrained the Southern Alps exhumation history since the Miocene, but Quaternary exhumation is hard to resolve precisely due to the very high exhumation rates. Likewise, GPS surveys estimate a vertical uplift of ~5 mm/yr, but integrate only over ~10 yr timescales and are restricted to one transect across the range.&lt;/p&gt;&lt;p&gt;To obtain insights into the Quaternary distribution and rates of exhumation of the western Southern Alps, we use new &lt;sup&gt;10&lt;/sup&gt;Be catchment-averaged erosion rates from 20 catchments along the western side of the range. Catchment-averaged erosion rates span an order of magnitude, between ~0.8 and &gt;10 mm/yr, but we find that erosion rates of &gt;10 mm/yr, a value often quoted in the literature as representative for the entire range, are very localized. Moreover, erosion rates decrease sharply north of the intersection with the Marlborough Fault System, suggesting substantial slip partitioning. These &lt;sup&gt;10&lt;/sup&gt;Be catchment-averaged erosion rates integrate, on average, over the last ~300 yrs. Considering that the last earthquake on the Alpine Fault was in 1717, these rates are representative of inter-seismic erosion. Lake sedimentation rates and coseismic landslide modelling suggest that long-term (~10&lt;sup&gt;3&lt;/sup&gt; yrs) erosion rates over a full seismic cycle could be ~40% greater than our inter-seismic erosion rates. If we assume steady state topography, such a scaling of our &lt;sup&gt;10&lt;/sup&gt;Be erosion rate estimates can be used to estimate rock uplift rates in the Southern Alps. Finally, we find that erosion, and hence potentially exhumation, does not seem to be localized at a particular distance from the fault, as some tectonic and provenance studies have suggested. Instead, we find that superimposed on the primary tectonic control, there is an elevation/temperature control on erosion rates, which is probably transient and related to frost-cracking and glacial retreat.&lt;/p&gt;&lt;p&gt;Our results highlight the potential for &lt;sup&gt;10&lt;/sup&gt;Be catchment-averaged erosion rates to provide insights into the magnitude and distribution of tectonic deformation rates, and the limitations that arise from transient erosion controls related to the seismic cycle and climate-modulated surface processes.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

Association of Dementia-Related Psychosis With Long-term Care Use and Death

Neurology ◽  
2021 ◽  
Vol 96 (12) ◽  
pp. e1620-e1631
Author(s):  
James B. Wetmore ◽  
Yi Peng ◽  
Heng Yan ◽  
Suying Li ◽  
Muna Irfan ◽  
...  
Keyword(s):  
Long Term Care ◽  
Fold Increase ◽  
Proportional Hazard ◽  
Comorbid Conditions ◽  
Term Care ◽  
Risk Of Death ◽  
Cox Proportional Hazard ◽  
Increased Risk ◽  
Cox Proportional Hazard Regression

ObjectiveTo determine the association of dementia-related psychosis (DRP) with death and use of long-term care (LTC); we hypothesized that DRP would be associated with increased risk of death and use of LTC in patients with dementia.MethodsA retrospective cohort study was performed. Medicare claims from 2008 to 2016 were used to define cohorts of patients with dementia and DRP. Outcomes were LTC, defined as nursing home stays of >100 consecutive days, and death. Patients with DRP were directly matched to patients with dementia without psychosis by age, sex, race, number of comorbid conditions, and dementia index year. Association of DRP with outcomes was evaluated using a Cox proportional hazard regression model.ResultsWe identified 256,408 patients with dementia. Within 2 years after the dementia index date, 13.9% of patients developed DRP and 31.9% had died. Corresponding estimates at 5 years were 25.5% and 64.0%. Mean age differed little between those who developed DRP (83.8 ± 7.9 years) and those who did not (83.1 ± 8.7 years). Patients with DRP were slightly more likely to be female (71.0% vs 68.3%) and white (85.7% vs 82.0%). Within 2 years of developing DRP, 16.1% entered LTC and 52.0% died; corresponding percentages for patients without DRP were 8.4% and 30.0%, respectively. In the matched cohort, DRP was associated with greater risk of LTC (hazard ratio [HR] 2.36, 2.29–2.44) and death (HR 2.06, 2.02–2.10).ConclusionsDRP was associated with a more than doubling in the risk of death and a nearly 2.5-fold increase in risk of the need for LTC.

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